Beef samples from five of six slaughterhouses in Poland have failed to detect any horse meat, it has been reported.

Irish authorities last week asserted that a consignment of beef trimmings imported from Poland for use in the production of beef burgers was the source of horse-DNA contamination in beef patties, resulting in tens of millions of them being pulled from supermarket freezers.

Polish authorities undertook to investigate, but no horse-meat contamination has been found to date.

The Polish news agency, PAP, quoted the deputy head of the Polish veterinary inspection Jaroslaw Naze as saying: “All 14 samples coming from the five slaughterhouses showed negative results, which means that horse protein was not detected.”

Results from the sixth slaughterhouse are expected today.

Irish officials said testing of the Polish ingredient concerned showed up to 20 per cent horse DNA content relative to beef.